1. Field of the Invention
The present invention relates to a power distributor for distributing electric power supplied from a power source such as a battery etc. mounted on a vehicle to a plurality of vehicle-mounted loads.
2. Description of the Related Art
Conventionally, as a means for distributing electric power supplied from a power source mounted on a vehicle to a plurality of vehicle-mounted loads, an electric coupling box is generally known in which a plurality of bus bar substrates are laminated to form a power distribution circuit, and fuses and relay switches are incorporated on the power distribution circuit.
Further, in recent years, in order to realize the miniaturization and high-speed switching control of such an electric coupling box, a power distributor has been developed in which each of semiconductor switching elements such as FETs etc. is disposed between an input terminal and an output terminal and each of the semiconductor switching elements is turned on and off by a control circuit incorporated in a control circuit board.
For example, Japanese Patent Laid-Open No. 126963/1998 discloses a power distributor which is arranged in a manner that a plurality of semiconductor switching elements (chips) are mounted on a control circuit board, then the conduction control terminals (control signal input terminals) of the semiconductor switching elements are connected to the control circuit of the control circuit board, then the input side conduction terminals of the respective semiconductor switching elements are connected to a power source through a common power source input terminal, and the output side conduction terminals of the respective semiconductor switching elements are connected to respective vehicle-mounted loads through power source output terminals.
However, according to the apparatus disclosed in this publication, since an external connection connector is provided in addition to the control circuit board, the input terminals and the output terminals, a special space is required for disposing the connector and further it is required to connect the connector to the control circuit board and the respective terminals by inner wirings. Thus, it is very difficult to miniaturize the entire size of the apparatus.
Further, according to this apparatus, since the respective semiconductor switching elements are mounted on the control circuit board, it is difficult to perform the heat dissipation (cooling) of the respective semiconductor switching elements. Thus, there may arise a case that the heat badly influences on other circuit elements mounted on the control circuit board.
As a means for avoiding such an inconvenience, it is considered to employ such a technique that the semiconductor switching elements are disposed at a portion other than the control circuit board and the semiconductor switching elements are connected to the control circuit board through a suitable connecting member. However, according to such a technique, it is further difficult to miniaturize the entire size of the apparatus.
Accordingly, the invention has been made in view of the aforesaid circumstances of the conventional technique, and an object of the invention is to provide a power distributor for a vehicle which can distribute electric power to a plurality of vehicle-mounted loads with a simple and compact configuration while a control circuit board is disposed separately from semiconductor switching elements.
To achieve the above object, according to the invention, there is provided a power distributor for a vehicle which distributes electric power supplied from a power source mounted on the vehicle to a plurality of vehicle-mounted loads, the power distributor comprising:
an input terminal coupled to the power source;
a plurality of output terminals coupled to the vehicle-mounted loads, respectively;
semiconductor switching elements disposed between the input terminal and the plurality of output terminals, respectively;
a control circuit board, disposed above the semiconductor switching elements, in which a control circuit is incorporated which controls on and off states of each of the semiconductor switching elements in accordance with a command signal inputted from outside;
board terminals for electrically connecting the control circuit to an external circuit; and
a casing for housing therein the semiconductor switching elements and the control circuit board, wherein
the semiconductor switching elements are disposed in one direction,
the input terminal, the output terminals and the board terminals are disposed in parallel to an arrangement direction of the semiconductor switching elements, and
the input terminal, the output terminals and the board terminals are protruded in a same direction from the casing to form a connector.
According to such a configuration, since the input terminal, the output terminals and the board terminals are disposed in parallel to the arrangement direction of the semiconductor switching elements and are protruded in the same direction from the casing to thereby directly form a connector, the entire size of the power distributor can be reduced largely. In particular, the width of the power distributor (the size of the power distributor along the direction perpendicular to the arrangement direction of the semiconductor switching elements) can be reduced largely. Thus, the entire size of the power distributor can be reduced to a large extent whilst the semiconductor switching elements are disposed separately from the control circuit board.
Further, when the semiconductor switching elements are disposed separately from the control circuit board as described above, the semiconductor switching elements can be positively cooled easily. For example, when the power distributor is arranged in a manner that a heat dissipation member is fixed to the lower surface of the casing in a state that the heat dissipation member is exposed outside of the casing so that the heat dissipation member is coupled to the semiconductor switching elements so as to be able to transmit heat therebetween, the respective semiconductor switching elements can be collectively cooled more efficiently.
In this respect, a coupling means between the input and output terminals and the control circuit board may be configured in a manner that tabs are raised from the respective terminals and coupled to the control circuit board. However, in this case, it is required an extra space for forming the tabs. In contrast, when the power distributor is arranged in a manner that the conduction control terminals of the respective semiconductor switching elements are coupled to the control circuit of the control circuit board through the flexible wiring member, the respective terminals can be coupled to the control circuit board with a more compact configuration.
In this case, the conduction control terminals of the respective semiconductor switching elements may be coupled to the flexible wiring member by directly coupling them to each other. In contrast, the power distributor may be arranged to further include control terminals which are disposed alternately with the output terminals and electrically coupled to the conduction control terminals of the semiconductor switching elements, respectively, and the control terminals may be coupled to the control circuit of the control circuit board through the flexible wiring member. In this case, the electrical coupling between the flexible wiring member and the respective conduction control terminals can be performed more simply and easily.
Although the number of the flexible wiring member is not limited, when such a flexible wiring member is employed, it is possible to electrically couple all the respective conduction control terminals to the control circuit by a sheet of the flexible wiring member, for example. In this case, the entire configuration of the power distributor can be more simplified.
Further, as well as the electrical coupling between the conduction control terminals and the control circuit, the control circuit is electrically coupled to the input terminal and the output terminals through the flexible wiring member, and the control circuit is arranged to, when a current value obtained from a voltage difference between the input terminal and one of the output terminals is equal to or more than a predetermined value, forcedly turn off the semiconductor switching element coupled to the one of the output terminals. In this case, each of the semiconductor switching elements can be provided with a fuse function by a simple wiring configuration.
In the invention, the concrete configurations of the respective terminals can be set suitably. For example, each of the board terminals may be formed by bending it at a center portion thereof to form almost a right angle between bent portions, wherein one ends of the board terminals are coupled to the control circuit of the control circuit board and other ends of the board terminals are disposed to protrude in a same direction as the input terminal and the output terminals. In this case, the electric coupling between the control circuit board and an external circuit can be realized reasonably with a simple configuration and further the entire size of the power distributor can be further miniaturized.
Further, when the semiconductor switching elements, the input terminal and the output terminals are disposed on the substantially same plane, and the control circuit board is disposed so as to be almost in parallel to the plane, not only the width of the power distributor but also the height thereof can be reduced largely (that is, the reduction in thickness can be realized).
Further, when the power distributor is arranged to further include a conduction plate on which the semiconductor switching elements are mounted and which is electrically coupled to input side conduction terminals of the semiconductor switching elements, and the conduction plate and the input terminal are formed by a common single metal plate, the number of the conductors constituting the circuit can be further reduced to thereby simplify the configuration and also the thickness of the power distributor can be further reduced.
Further, it is possible to mold the input terminal, the output terminals and the board terminals integrally with the casing. In this case, the entire configuration of the power distributor can be further simplified.
Furthermore, when a connector housing portion covering the input terminal, the output terminals and the board terminals is formed integrally with one side surface of the main body of the casing, the respective terminals can be surely protected and the respective terminals can be coupled to the connector on the external wiring side more simply.